To solve the problem on automatic behavior control of a micro wall-climbing robot when its suction foot was not fulfilled enough vacuum pressure on an unsmoothed wall, a motion control method based on initiative exploration was proposed. Firstly the basic gaits of the micro wall-climbing robot were analyzed. Then a finite state machine model of the suction foot of the robot was introduced. In addition, the priority to transfer the state was defined according to the "handy" principle. The above-mentioned studies provided the foundation for the motion control method based on initiative exploration. Simulations and experiments show that the method can easily control the micro wall-climbing robot to search a proper touchdown point for its suction foot on the unsmoothed wall.